Thermoplastic.....crashing through hard snowbanks at 10 degrees doesn't work if you want to keep your mud flaps
I've heard the ones now that are sold by toyota dealers are just cheap plastic replicas, yet sold under the toyota part number. The original toyota mud flaps on my truck are labeled which wheel well their for, and have a part number bossed into them. From what I've been told the replacement ones aren't.....it's another reason why I choose to get an original off eBay.....matches the others perfect.